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What does it cost to get drawings for a carport or shed?

A drawing set from a design office typically costs a modest fee — but for a small structure you can often draw what the authority needs yourself. The expensive part is rarely the drawing; it's the boundary.

What typically has to be submitted

Even for a small building, the wish list is, as a general rule, the same as for a house — just on a smaller scale:

• Site plan: the plot seen from above with the new building drawn in, distances to the boundary and to other buildings, and ideally the cadastral lines.
• Floor plan: the building seen from above, to scale — typically 1:50 or 1:100 — with external measurements.
• Section: the building cut through, so heights, roof structure and floor level are visible.
• Elevations: all four sides, with heights and materials.
• Area information: the built-up area, and how it affects the plot's overall building coverage ratio.

That's the set a design office charges for. What's precisely required in a given case depends on where the building is going and how big it is — and on whether planning permission is required at all, or whether a simple notification will do.

When you can draw it yourself

A carport is a rectangle with a roof on it. With a laser measure, a sheet of graph paper or a drawing program — and the ability to hold a consistent scale — most people can produce a floor plan, section and elevations of a quality a caseworker can read. The requirement isn't beauty, but legibility and dimensioning: the scale has to be stated on the drawing, all external measurements have to be shown, and heights have to be measured from a defined level, typically ground level.

What typically can't be drawn yourself is the site plan — not because it's hard to draw, but because the distances to the boundary have to be correct. If the boundary is marked with secure boundary posts, you can measure it yourself. If it's a hedge or a fence, you don't actually know where the boundary runs, and a carport that ends up 60 cm out of place is an expensive mistake. If there's any doubt, a licensed surveyor has to mark out the boundary. It's a noticeable expense — and still cheaper than moving a finished carport.

The calculation people most often get wrong: the building coverage ratio

A carport or a shed counts, in many cases, towards the plot's built-up area, and that's where projects run aground. An example: a plot of 800 m² with an allowed building coverage ratio of 30% can carry 800 × 0.30 = 240 m² of building. The house takes up 172 m². That leaves 68 m². A double carport of 36 m² and a shed of 15 m² together take up 51 m² — that fits. But if there's already a covered terrace of 24 m² that counts too, there's only 44 m² left, and then it doesn't.

How much of a carport or a shed counts, and what deductions apply, depends on the local rules and on the specific plan that applies to the plot. Ask the local planning department with your own figures in hand — it costs nothing, and it can save an entire project.

What you need to have measured before you draw

1. The plot's dimensions and its fixed points: house, driveway, trees, drains and existing buildings.
2. The distance from the house to the boundary on the sides where the building is going.
3. The slope of the ground. If the plot falls 40 cm along the carport's length, that changes both the foundation and the heights on the elevation drawing.
4. The house's facade heights and roof pitch, if the carport is going to be built up against the house. A measured plan of the house helps here, as a base to draw the carport from — in HouseSense the home can be scanned or drawn and the plan exported as a PDF with real measurements, so the extension gets drawn on top of reality rather than a guess.
5. The plot's existing built-up area, measured building by building, so the coverage ratio can be calculated honestly.

What the drawing can't answer

A drawing shows what you want to build. It doesn't decide whether you're allowed to. Three things need to be looked up elsewhere:

• Local plans and covenants for the address can set requirements on placement, roof shape, materials and colours.
• Boundary-distance requirements are measured from the cadastral boundary, not from the hedge.
• Whether the building requires planning permission or just a notification depends on its type, size and placement — and that's decided by the local authority on a case-by-case basis.

If the carport is going to be joined to the house, or an opening has to be made in the house's outer wall, it's no longer a small structure: structural questions come into play, and no drawing, scan or app can determine whether a wall is load-bearing. That requires a building surveyor or a consulting structural engineer who inspects the structure on site.

The cheapest order to do things in

1. Look up the local plan and covenants for the address, and ask the local authority about the project in broad strokes.
2. Calculate the coverage ratio on the plot's actual built-up area before drawing anything.
3. Establish whether the boundary is secure. If it isn't, get it marked out before the carport is positioned.
4. Draw the floor plan, section and elevations yourself, if that's accepted — it's the cheapest item to take on.
5. Only pay for what's actually being asked for.

This article is not legal advice. The requirements in any individual case are decided by the local authority, and they vary from municipality to municipality and from country to country.